It is oftentimes desirable for liquid chemicals to be transferred from a supply tank in precise volumetric quantities. For example, liquid agricultural chemicals (e.g., pesticides, herbicides, fertilizers and the like) are oftentimes mixed with water in precise amounts by growers for application to crops. Because of the desire to minimize (if not eliminate entirely) exposure to the agricultural chemicals during the transfer procedure, it is typically not satisfactory for the agricultural chemicals to simply be poured into the mixing tank. Instead, the growers must use a "dosed" transfer system (i.e., a system which is not open to ambient environment but allows transfer of the agricultural chemical directly from the supply tank to the mixing tank).
Recently, a portable, self-contained closed chemical transfer system has been proposed in U.S. Pat. No. 5,199,472 issued on Apr. 6, 1993 to Gfi Rollison (the entire content of which is expressly incorporated hereinto by reference). According to the Rollison '472 patent, a closed chemical transfer system is provided which includes a metering canister and the means for applying a vacuum to the canister so as to allow liquid chemical to be transferred from a separate supply tank and into the canister. By releasing the vacuum in the canister and closing the liquid chemical supply line thereto, the liquid chemical in the canister may then be transferred to another tank.
While the transfer system disclosed in the Rollison '472 patent represents a satisfactory solution for the "dosed" transfer of liquid chemicals, some improvements are still desirable. For example, it would especially be desirable if the liquid chemical transfer system disclosed in the Rollison '472 patent was provided with a liquid chemical tank supply assembly so that the entire tank assembly and transfer system could be transported as an integral unit to agricultural fields. It is towards providing such an improvement that the present invention is directed.
In general, the present invention is embodied in a self-contained, portable liquid chemical supply tank storage and transfer unit. The unit is generally comprised of an external support shell having upper and lower support shell sections joined to one another. The upper support shell section includes diametrically opposed upright arms which define therebetween a generally U-shaped space in which the transfer system is positioned. The lower support shell section houses a liquid chemical storage tank.
The transfer system includes a metering canister fluid-connected to the liquid chemical within the storage tank, a selector valve assembly and a pump (preferably a manually-actuated hand pump). Operation of the pump will be evacuate the canister to thereby allow liquid chemical to be drawn from the storage tank and into the canister. The liquid chemical in the metering canister may then be transferred (e.g., via gravity or another pump) to another tank, for example, a mixing tank associated with an agricultural spray implement. In such a manner, therefore, transference of the liquid chemical to another tank is accomplished without exposing the user to the liquid chemical thereby transferred, while also permitting the liquid chemical to be transported easily to its intended use site.
Further aspects and advantages of this invention will become more clear after careful consideration is given to the detailed description of the preferred exemplary embodiments thereof which follow.